Uptake and assimilability of nickel in the course of systemic allergy: Implications for elimination diet

•We report a mean nickel uptake of 227 μg/day for people aged 20-25.•We report a mean nickel uptake of 161 μg/day for people aged 40-50.•We examine nickel release during simulated digestion.•We determine 50% release for nickel contained in nuts and chocolate.•The nickel amount determined in serum plotted against the uptaken amount yields 16%.

The average nickel uptake in the group of students aged 20 to 25 was determined at 227 μg/day. The same study conducted among 9 senior researchers aged 40 to 50 brought a mean nickel uptake of 161 μg/day. Trace amounts of nickel are present in the majority of foodstuffs. Absorbed from digested aliment, its ions are directly responsible for the occurrence of allergic symptoms. Assimilation of nutrients varies with individual susceptibility and overall health condition. However, it also has a lot to do with dietary habits and food characteristics. In this manuscript, we delineated main parameters related to nickel accumulation, such as its uptake, release from foodstuffs and assimilability. Each of them, their scale and proportions potentially affect allergic response from hypersensitive organism. We analyzed several nickel-rich commodities of various characteristics for their nickel level with a particular interest in the metal amounts being released from digested matter and their proportions. Quantitatively profiled samples of chocolate (3-5 μg nickel/g), popular plant products (1-4 μg/g), nuts (1-10 μg/g) and herbal spices (0.3-10.8 μg/g) underwent simulated digestion followed by atomic absorption spectrometry measurements to evaluate nickel release ratio. Groups of samples composed of analogous food matrices showed consistent release rates. As opposed to chocolate and nuts (both average 50% release), less homogenous individual herbal spice samples indicated nickel release between 20% and 90%. The release ratio gives an idea of how much metal allergen is available for assimilation out of the total intake of food-borne nickel. Absorption ratio accounts for the amount that ultimately supplies blood serum. We determined mean nickel absorption rate at 16% relative to the daily uptake. Elimination diets should acknowledge release rates specific to individual nutrients as their criterion in designing aware consumption. Apart from crude quantitative approach, specific biochemical food characteristics should be considered in the context of systemic hypersensitivities related to exogenous nickel uptake.